It is anticipated that the following objectives will be realized as a result of the proposed program: 1.) To restore function at the joint when destroyed or otherwise defective as a result of arthritis, injury or birth defect. 2.) To provide as near normal function as possible by correction of deformity and restoration of the biomechanics of the joint utilizing residual muscle power and ligamentous stability. 3.) To provide endoprostheses (total joint replacements) for these needs, which are durable (especially minimal wear of component materials), which can be fabricated and sterilized with ease, and which will not require extraordinary operation procedure or follow up care. Two types of total knee joint replacements are visualized: anatomical, resurfacing or floating type for arthritic joints where deformity can be corrected and stability restored by excising bone and ligamentous stock. Reconstruction by hinge or inherently stable type where deformity and/or instability necessitates prosthetic intrinsic stability. Total shoulder or elbow joint replacements will be considered and prototypes developed. 4) To provide initial and enduring intraosseous skeletal fixation of the components.